Longitudinal structural behavior of shield tunnel with large diameter and small curvature

Abstract

The structural mechanism of a large-diameter curved tunnel is introduced in detail because no relevant calculation method is available. A longitudinal discontinuous contact model is established based on the newly built North Highway Tunnel in Shanghai, China. First, the load-spreading mechanism of circumferential joints was considered. Second, the distribution laws of the longitudinal internal force, settlement, and joint deformation of curved and straight tunnels under the same load were analyzed and compared. Finally, a model test is conducted to verify the effectiveness of the discontinuous contact model. The results indicated that with an increase in the radius of curvature, the maximum internal force and deformation decreased. The internal forces and deformations of straight and curved tunnels are quite different; therefore, the design method for a straight tunnel cannot be used in the design of curved tunnels. The overall and local deformations of the curved tunnel were affected by end displacement.